Question

Which reaction shows that the enthalpy of formation of CS2 is Hf = 89.4 kJ/mol?

A. C(s) + 2S(s) CS2(l) + 89.4 kJ
B. C(s) + 2S(s) + 89.4 kJ CS2(l)
C. C(s) + 2S(s) + 89.4 kJ CS2(l) + 89.4 kJ
D. C(s) + 2S(s) CS2(l)

I think the answer is a or b

Answer 1

Why not add arrows for clarity? That's what they're for. Have I put them in at the right place? Only the author knows.
A. C(s) + 2S(s)==> CS2(l) + 89.4 kJ
B. C(s) + 2S(s) + 89.4 kJ ==>CS2(l)
C. C(s) + 2S(s) + 89.4 kJ ==> CS2(l) + 89.4 kJ
D. C(s) + 2S(s) ==> CS2(l)

It can't be A because that shows 89.4 kJ heat RELEASED and dH is + 89.4. For heat to be released dH must be -.
B shows it uses heat and is endothermic which is + 89.4
C. You NEVER see dH on BOTH sides of the same equation.
D. It can't be D because it has no dH at all.

Answer 2

so whats the answer???

Answer 3

its b